Deacetyl­ tenuazonic acid

Abstract

The heterocycle in the title compound {systematic name: (5S)-5-[(1S)-1-methyl­prop­yl]pyrrolidine-2,4-dione}, C₈H₁₃NO₂, is planar (r.m.s. deviation for all non-H atoms = 0.008 Å). The crystal structure is stabilized by N—H⋯O hydrogen bonding.

Related literature

Tenuazonic acid (TA) is an Alternaria mycotoxin commonly encountered in food (Siegel, Rasenko et al., 2009 ▶; Weidenbörner, 2001 ▶). The title compound is known to be formed upon boiling TA in 0.1 M HCl (Stickings, 1959 ▶). For the synthesis of the title compound, see: Lebrun et al. (1988 ▶). For the crystal structure of the tenuazonic acid copper (II) salt, see: Dippenaar et al. (1977 ▶) and for the 2,4-dinitro­phenyl­hydrazone, see: Siegel, Merkel et al. (2009 ▶). For the structures of other pyrrolidine-2,4-diones, see, for example: Yu et al. (2007 ▶); Zhu et al. (2004 ▶); Ellis & Spek (2001 ▶).

Experimental

Crystal data

• C₈H₁₃NO₂

• M _r = 155.19

• Monoclinic,

• a = 5.0114 (4) Å

• b = 7.7961 (4) Å

• c = 10.9919 (10) Å

• β = 95.778 (4)°

• V = 427.26 (6) ų

• Z = 2

• Cu Kα radiation

• μ = 0.71 mm⁻¹

• T = 193 K

• 0.44 × 0.16 × 0.16 mm

Data collection

• Enraf–Nonius CAD-4 diffractometer

• Absorption correction: ψ scan (CORINC; Dräger & Gattow, 1971 ▶) T _min = 0.744, T _max = 0.993 (expected range = 0.669–0.893)

• 1866 measured reflections

• 1571 independent reflections

• 1558 reflections with I > 2σ(I)

• R _int = 0.040

• 3 standard reflections frequency: 60 min intensity decay: 2%

Refinement

• R[F ² > 2σ(F ²)] = 0.036

• wR(F ²) = 0.098

• S = 1.06

• 1571 reflections

• 103 parameters

• 1 restraint

• H-atom parameters constrained

• Δρ_max = 0.22 e Å⁻³

• Δρ_min = −0.17 e Å⁻³

• Absolute structure: Flack (1983 ▶), 697 Friedel pairs

• Flack parameter: 0.1 (2)

Data collection: CAD-4 Software (Enraf–Nonius, 1989 ▶); cell refinement: CAD-4 Software; data reduction: CORINC (Dräger & Gattow, 1971 ▶); program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEPIII (Burnett & Johnson, 1996 ▶); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 ▶).

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O1i	0.90	2.02	2.8963 (18)	164

Symmetry code: (i) .

supplementary crystallographic information

Comment

Tenuazonic acid (TA) is an Alternaria mycotoxin commonly encountered in food (Siegel, Rasenko et al., 2009; Weidenbörner, 2001). The title compound is known to be formed upon boiling of TA in 0.1 M HCl (Stickings, 1959). It is therefore a possible degradation product which might also be encountered in food matrices.

Whereas TA itself could so far only be crystallized as its copper (II) salt (Dippenaar et al., 1977) or 2,4-dinitrophenylhydrazone (Siegel, Merkel et al., 2009), the title compound is conveniently crystallized from hexane/ethyl acetate.

Each molecule (Fig. 1) is connected to two adjacent molecules via N—H···O hydrogen bonds. Along the b axis chains of symmetry equivalent molecules are formed (Fig. 2).

Experimental

The title compound was supplied by the workgroup of Professor R. Faust (University of Kassel, Germany) by synthesis according to a literature procedure (Lebrun et al., 1988). For x-ray analysis, it was recrystallized several times from hexane:ethyl acetate 50:50 (v:v).

Refinement

The hydrogen atoms were located in difference maps but positioned with idealized geometry and refined using the riding model, with C—H = 0.98–1.00 Å or N—H = 0.90 Å and U_iso(H) = 1.2U_eq(C,N) or 1.5U_eq(C_methyl).

Figures

Fig. 1.

ORTEP representation of the title compound with atomic labeling of, shown with 50% probability displacement ellipsoids.

Fig. 2.

View of the unit cell of the title compound along [100], showing the hydrogen-bonded chains running along the twofold screw axis.

Crystal data

C8H13NO2	F(000) = 168
Mr = 155.19	Dx = 1.206 Mg m−3
Monoclinic, P21	Cu Kα radiation, λ = 1.54178 Å
Hall symbol: P 2yb	Cell parameters from 25 reflections
a = 5.0114 (4) Å	θ = 67–69°
b = 7.7961 (4) Å	µ = 0.71 mm−1
c = 10.9919 (10) Å	T = 193 K
β = 95.778 (4)°	Block, yellow
V = 427.26 (6) Å3	0.44 × 0.16 × 0.16 mm
Z = 2

Data collection

Enraf–Nonius CAD-4 diffractometer	1558 reflections with I > 2σ(I)
Radiation source: rotating anode	Rint = 0.040
graphite	θmax = 69.9°, θmin = 4.0°
ω/2θ scans	h = −6→5
Absorption correction: ψ scan (CORINC; Dräger & Gattow, 1971)	k = −8→9
Tmin = 0.744, Tmax = 0.993	l = −13→13
1866 measured reflections	3 standard reflections every 60 min
1571 independent reflections	intensity decay: 2%

Refinement

Refinement on F2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F2 > 2σ(F2)] = 0.036	w = 1/[σ2(Fo2) + (0.0616P)2 + 0.0771P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.098	(Δ/σ)max < 0.001
S = 1.06	Δρmax = 0.22 e Å−3
1571 reflections	Δρmin = −0.16 e Å−3
103 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
1 restraint	Extinction coefficient: 0.017 (4)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), 697 Friedel pairs
Secondary atom site location: difference Fourier map	Flack parameter: 0.1 (2)

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	−0.0559 (2)	0.66044 (16)	0.50335 (11)	0.0386 (3)
O2	0.5911 (3)	0.74694 (19)	0.22570 (14)	0.0494 (4)
N1	0.2318 (3)	0.48864 (18)	0.41048 (11)	0.0303 (3)
H1	0.1866	0.3946	0.4519	0.036*
C1	0.1196 (3)	0.6392 (2)	0.43372 (14)	0.0305 (3)
C2	0.2400 (3)	0.7779 (2)	0.36022 (15)	0.0360 (4)
H2A	0.1012	0.8320	0.3021	0.043*
H2B	0.3265	0.8675	0.4145	0.043*
C3	0.4437 (3)	0.6853 (2)	0.29328 (15)	0.0335 (4)
C4	0.4354 (3)	0.4941 (2)	0.32393 (13)	0.0296 (3)
H4	0.6122	0.4594	0.3672	0.036*
C5	0.3757 (3)	0.3822 (2)	0.20975 (14)	0.0317 (4)
H5	0.5040	0.4161	0.1500	0.038*
C6	0.0924 (4)	0.4130 (3)	0.14885 (16)	0.0425 (4)
H6A	−0.0373	0.3594	0.1995	0.051*
H6B	0.0571	0.5380	0.1467	0.051*
C7	0.0441 (6)	0.3429 (4)	0.0202 (2)	0.0761 (8)
H7A	0.1721	0.3946	−0.0307	0.114*
H7B	−0.1391	0.3706	−0.0138	0.114*
H7C	0.0679	0.2181	0.0219	0.114*
C8	0.4266 (4)	0.1937 (2)	0.2416 (2)	0.0474 (5)
H8A	0.6088	0.1804	0.2821	0.071*
H8B	0.4071	0.1250	0.1666	0.071*
H8C	0.2967	0.1549	0.2966	0.071*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
O1	0.0498 (7)	0.0316 (6)	0.0377 (6)	−0.0010 (5)	0.0201 (5)	−0.0054 (5)
O2	0.0530 (8)	0.0418 (8)	0.0576 (8)	−0.0067 (6)	0.0262 (6)	0.0115 (6)
N1	0.0349 (7)	0.0268 (7)	0.0303 (6)	−0.0028 (5)	0.0094 (5)	0.0017 (5)
C1	0.0374 (8)	0.0264 (8)	0.0279 (7)	−0.0056 (6)	0.0046 (6)	−0.0030 (6)
C2	0.0462 (9)	0.0253 (8)	0.0378 (8)	−0.0062 (7)	0.0104 (7)	−0.0022 (7)
C3	0.0348 (8)	0.0312 (8)	0.0347 (8)	−0.0065 (6)	0.0043 (6)	0.0024 (7)
C4	0.0268 (7)	0.0308 (8)	0.0321 (7)	−0.0025 (6)	0.0063 (5)	0.0042 (7)
C5	0.0310 (8)	0.0312 (8)	0.0346 (8)	0.0006 (6)	0.0120 (6)	−0.0011 (6)
C6	0.0373 (9)	0.0512 (11)	0.0391 (9)	0.0028 (7)	0.0037 (7)	−0.0102 (8)
C7	0.0824 (18)	0.087 (2)	0.0547 (14)	0.0218 (14)	−0.0144 (12)	−0.0302 (13)
C8	0.0558 (11)	0.0317 (9)	0.0573 (12)	0.0060 (8)	0.0182 (8)	−0.0003 (8)

Geometric parameters (Å, °)

O1—C1	1.2338 (19)	C5—C8	1.526 (2)
O2—C3	1.199 (2)	C5—C6	1.526 (2)
N1—C1	1.337 (2)	C5—H5	1.0000
N1—C4	1.4640 (18)	C6—C7	1.512 (3)
N1—H1	0.9038	C6—H6A	0.9900
C1—C2	1.511 (2)	C6—H6B	0.9900
C2—C3	1.501 (2)	C7—H7A	0.9800
C2—H2A	0.9900	C7—H7B	0.9800
C2—H2B	0.9900	C7—H7C	0.9800
C3—C4	1.530 (2)	C8—H8A	0.9800
C4—C5	1.533 (2)	C8—H8B	0.9800
C4—H4	1.0000	C8—H8C	0.9800
C1—N1—C4	115.63 (14)	C6—C5—C4	111.45 (13)
C1—N1—H1	119.0	C8—C5—H5	107.6
C4—N1—H1	125.2	C6—C5—H5	107.6
O1—C1—N1	125.18 (14)	C4—C5—H5	107.6
O1—C1—C2	125.70 (14)	C7—C6—C5	114.04 (16)
N1—C1—C2	109.12 (14)	C7—C6—H6A	108.7
C3—C2—C1	104.25 (14)	C5—C6—H6A	108.7
C3—C2—H2A	110.9	C7—C6—H6B	108.7
C1—C2—H2A	110.9	C5—C6—H6B	108.7
C3—C2—H2B	110.9	H6A—C6—H6B	107.6
C1—C2—H2B	110.9	C6—C7—H7A	109.5
H2A—C2—H2B	108.9	C6—C7—H7B	109.5
O2—C3—C2	127.06 (17)	H7A—C7—H7B	109.5
O2—C3—C4	123.96 (16)	C6—C7—H7C	109.5
C2—C3—C4	108.98 (13)	H7A—C7—H7C	109.5
N1—C4—C3	101.98 (13)	H7B—C7—H7C	109.5
N1—C4—C5	115.10 (13)	C5—C8—H8A	109.5
C3—C4—C5	112.44 (13)	C5—C8—H8B	109.5
N1—C4—H4	109.0	H8A—C8—H8B	109.5
C3—C4—H4	109.0	C5—C8—H8C	109.5
C5—C4—H4	109.0	H8A—C8—H8C	109.5
C8—C5—C6	112.26 (15)	H8B—C8—H8C	109.5
C8—C5—C4	110.21 (14)
C4—N1—C1—O1	179.64 (15)	C2—C3—C4—N1	−1.75 (16)
C4—N1—C1—C2	0.22 (18)	O2—C3—C4—C5	−57.6 (2)
O1—C1—C2—C3	179.26 (14)	C2—C3—C4—C5	122.08 (14)
N1—C1—C2—C3	−1.33 (18)	N1—C4—C5—C8	−75.53 (17)
C1—C2—C3—O2	−178.44 (17)	C3—C4—C5—C8	168.27 (14)
C1—C2—C3—C4	1.90 (17)	N1—C4—C5—C6	49.81 (19)
C1—N1—C4—C3	0.95 (16)	C3—C4—C5—C6	−66.39 (17)
C1—N1—C4—C5	−121.07 (15)	C8—C5—C6—C7	−70.6 (3)
O2—C3—C4—N1	178.57 (16)	C4—C5—C6—C7	165.2 (2)

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1i	0.90	2.02	2.8963 (18)	164

Symmetry codes: (i) −x, y−1/2, −z+1.